<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
#one{width:100px; height:100px; background:red; position:absolute;left:0px;top:50px;}
</style>
<script>

var timer=null;
function startMove(target){
	var one=document.getElementById('one');
	clearInterval(timer);
	timer=setInterval(function(){
		var speed=0;
		if(one.offsetLeft<target){
			speed=7;	
		}else{
			speed=-7;	
		};
		if(Math.abs(one.offsetLeft-target)<speed){
			clearInterval(timer);
			one.style.left=target+'px';	
		}else{
			one.style.left=one.offsetLeft+speed+'px';	
		};	
		
	},30);	
};


</script>
</head>

<body>
<input type="button" value="运动" onclick="startMove(300)" />
<div id="one"></div>
<span style=" position:absolute;left:300px; height:500px;width:1px; background:#000;"></span>

</body>
</html>
